Large voltage control of magnetic anisotropy in CoFeB/MgO/OX structures at room temperature

Fen Xue,Shan X Wang,Jinliang He,Noriyuki Sato,Jun Hu,Chong Bi

doi:10.1063/1.5101002

Fen Xue, Shan X Wang + Show 4 more

Open Access

https://doi.org/10.1063/1.5101002

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Journal: APL materials	Publication Date: Oct 1, 2019
Citations: 11	License type: cc-by

Affiliation: Tsinghua University, Stanford University

Abstract

Voltage control of magnetic anisotropy (VCMA) provides an energy-efficient approach to manipulate spintronic devices. Currently, VCMA only shows a weak effect in magnetic tunnel junctions (MTJs) composed of CoFeB/MgO/CoFeB that are the core structure of spintronic memories and logic devices. Multiple approaches have been proposed and studied by researchers to increase the VCMA effect. Here, we demonstrate a large VCMA effect in the CoFeB/MgO/SiO2 double-oxide structure, which can be potentially modified to be compatible with the MTJ cell. The VCMA coefficient as high as 174 fJ/Vm is achieved in this structure at room temperature, with its magnitude comparable to the reported ion-driven VCMA with a high ion-conductive oxide at an elevated temperature. Theoretical analysis indicates that the large VCMA is a magnetoionic effect, which is dominated by ion migration and can be explained by a nanograin cluster model. This double-oxide structure is promising to be extended to an MTJ structure to reduce switching energy in spintronic devices.

Highlights

Pursuing low power memory devices is so critical to enable the architecture of processing-in-memory computing
Until voltage control of magnetic anisotropy (VCMA) is proposed as an alternative approach to manipulate spintronic devices, the writing power is expected to be lowered down quite a bit
In magnetic tunnel junctions (MTJs) structures, the CoFeB/MgO/CoFeB trilayer is fundamental to gain high tunneling magnetoresistance (TMR) ratio and perpendicular magnetic anisotropy (PMA), and ionic conductors cannot be directly applied adjacent to the CoFeB layer

Summary

Introduction

Pursuing low power memory devices is so critical to enable the architecture of processing-in-memory computing. In order to study the VCMA effect, a gate voltage Vg is applied and large electric fields are generated at the CoFeB|MgO and MgO|SiO2 interfaces, and across the oxide layers as well.

Results

Conclusion